Severe combined immunodeficiency in the newborn

Severe combined immunodeficiencies (SCIDs) are a group of rare diseases of T-lymphocyte or thymic failure, which comprise the most severe immunodeficiencies. Generally fatal by one year of age without treatment, they constitute a paediatric emergency and early diagnosis facilitates a better prognosis. This article will review the molecular mechanisms of SCID, clinical signs and symptoms, diagnostic investigations and review treatment modalities and outcomes, and discuss future developments.